The invention concerns a perpendicular connection of two profile rods with undercut linear grooves abutting at an angle, with a connecting bolt which has a head at one end and is arranged parallel to the axis of symmetry of a longitudinal profile rod and arranged in an undercut linear groove therein, and with its other end engages in a tenon block arranged in an undercut linear groove of the transverse profile rod and with its head engages behind a spread element with a through bore for the connecting bolt inserted in the undercut linear groove where, under the effect of an axial force which can be exerted by the connecting bolt, the spread element can be spread transverse to the linear groove and firmly clamped in this as an abutment.
DE-A 3438773 describes a perpendicular connection with a connecting bolt of two profile rods with undercut linear grooves abutting at right angles. The connecting bolt is arranged parallel to the axis of symmetry of a longitudinal profile rod in an undercut linear groove therein and with its end remote from the bolt head engages in a tenon block arranged in an undercut linear groove of the transverse profile rod. With its head the connecting bolt engages behind a cylindrical abutment piece which is fitted, axially fixed, in the undercut linear groove of the profile rod and has a through bore for the connecting bolt. For assembly it is necessary to produce cylindrical recesses in the connecting profile rod to be connected, across its length, in order to be able to accommodate the cylindrical abutment piece. Furthermore, a fixing point is always marked by the evident cylindrical abutment piece. Finally, once fitted with cylindrical transverse bores, a profile rod can no longer be re-used universally as the transverse bores always remain evident.
DE-A 4016320 discloses a perpendicular connection of profile rods which is based on the perpendicular connection described in DE-A-3438773, with a cylindrical abutment piece which can be inserted in the linear groove. The external diameter of the cylindrical abutment piece is adapted to the cross-section of the undercut linear groove of the profile rod so that a thread applied on the outer periphery of the cylindrical abutment piece acts as a self-tapping thread engaging in the material of the profile rod. In this perpendicular connection the cylindrical recesses on the long sides of the profile rod to be connected can be omitted. One substantial disadvantage of the perpendicular connection with an abutment piece with self-tapping thread, however, is that because of the thread to be cut, insertion of the abutment pieces requires a great force which quickly leads to fatigue and pain in the wrist of the fitter who produces several perpendicular connections in succession.
DE-A-4343381 discloses a connecting element for production of a perpendicular connection of profile rods of the type described initially, with a spread element. The spread element consists of two spread parts which face each other with wedge surfaces running obliquely to the longitudinal axis of the connecting bolt at an angle of 45xc2x0. A substantial disadvantage of this connection type is that due to the asymmetric spread, locally different contact forces are generated between the spread body and the linear groove which in total leads to inadequate fixing of the spread body in the linear groove.
The invention is therefore based on the task of creating a perpendicular connection of the type described initially with which a good clamping effect can be achieved.
The task is solved according to the invention in that the spread element comprises a spread body with an axial holder bore and a wedge body which can be inserted therein, with a through bore for the connecting bolt, where the head of the connecting bolt lies against a face of the wedge body.
This symmetrical arrangement of two interlinking parts of the spread element gives a force effect which is evenly distributed over the surface of the spread body and which even at low tightening torques of the connecting bolt leads to a high surface pressure and hence excellent clamping of the spread body serving as an abutment in the linear groove.
The spread body can be formed of one piece. It is also possible for the spread body to made as a package of individual components, arranged in linear succession, made of sheet steel punched as a package. In the latter variant the external shape of the spread element and the creation of the holder bore are considerably simplified as the cutting machining to produce the spread body with a preset cross-section, in particular from a blank of hard material, is more time-consuming and expensive than punching out and packaging individual plate segments.
Suitably the cross-section of the spread body is adapted to the cross-section of the linear groove of the profile rod so that on spreading, practically the entire surface of the spread body lies against the inner wall of the linear groove and thus leads to the greatest possible contact area.
Preferably to facilitate the spreading the spread body has a longitudinal slot. In a preferred design of the perpendicular connection according to the invention, the wedge body is aligned in the spread body with its wedge tip towards the tenon block.
An extremely even distribution of contact forces between the spread body and the linear groove is obtained as the inner surface of the spread body interacting with the wedge body is formed sloping corresponding to the wedge slopes of the wedge body.
Preferably the wedge body is a sleeve with tapered generating surface where the spread body has a tapered inner surface.
To increase the stability of the perpendicular connection, the surface of the spread body facing the inner surface of the linear groove is at least partly roughened, or fitted with protrusions or recesses, in particular grooves, scoring or teeth For a particularly firm and tight-fitting connection, the roughening or protrusions are designed as tips forming barbs.
The perpendicular connection according to the invention is preferably used for constructions with profile rods of aluminium or another alloy The individual parts of the connecting element are preferably made of steel or another hard metal. With this material combination, in particular with toothed surfaces of the spread body, extremely tight-fitting, twist-resistant and stable perpendicular connections are obtained Naturally however the perpendicular connection according to the invention can be used with other materials for the profile rods and components of the connecting element, e.g. plastics or plastic/metal composite materials.
The perpendicular connections according to the invention are particularly suitable for the simple construction of machine frames, working tables, transport lines and similar, from constructions made from individual abutting profile rods which are held together by hidden connecting bolts.